Plasma display panel device

ABSTRACT

A plasma display panel device has a pair of electrodes arranged to face with each other with a sealed discharging gap therebetween in which a dischargeable gas is filled. When a voltage is impressed between the electrodes an electrical discharge of the gas will be caused and provide luminescence to display a character, such as a letter or a figure in accordance with the selected electrodes. Only one insulating layer, which covers one of the pair of the electrodes, is needed to effectively operate the display. A wall charge having an opposite polarity to that of the electrode voltage is provided on the insulating layer whereby a decrease of the electrode voltage can be prevented and the memory function, capable of turning &#39;&#39;&#39;&#39;on&#39;&#39;&#39;&#39; (to write) and &#39;&#39;&#39;&#39;off&#39;&#39;&#39;&#39; (to erase) by impressing a write pulse or an erase pulse, is formed. The single insulating layer enables a decrease of the operation voltage, a high resolution and an accurate writing and erasing to be realized.

United States Patent 91 Kurahashi et al.

[ Feb. 11, 1975 1 PLASMA DISPLAY PANEL DEVICE [73] Assignee: MitsubishiDenki Kabushiki Kaisha,

Tokyo, Japan 221 Filed: June 9,1972

[21] Appl.No.:261,291

[30] Foreign Application Priority Data June 22, 1971 Japan 46-44973 Oct.28, 1971 Japan 46-100413 [52] US. Cl 313/510, 313/188, 313/201, 313/514,315/169 TV [51] Int. Cl. H01j 7/42, HOlk 1/60 [58] Field of Search313/188, 201, 220, 109.5, 313/174, 203',3l5/169TV [56] References CitedUNITED STATES PATENTS 1,889,852 12/1932 Davis 315/169 TV X 2,004,5776/1935 Lebedenko et al. 313/1095 2,847,615 8/1958 Engelbart 313/201 X3,127,535 3/1964 Westerheim 313/1095 3,499,167 3/1970 Baker et al.315/169 TV 3,559,190 l/l97l Bitzer et a1. 313/201 X 3,562,737 2/1971Wiederhorn et al........ 315/169 R X 3,629,638 12/1971 Veron et a1313/201 X Kupsky 313/174 Walters 313/188 Primary Examiner-James W.Lawrence Assistant Examiner-Saxfield Chatmon, Jr. Attorney, Agent, orFirm-Oblon, Fisher, Spivak, McClelland & Maier [57] ABSTRACT A plasmadisplay panel device has a pair of electrodes arranged to face with eachother with a sealed discharging gap therebetween in which adischargeable gas is filled. When a voltage is impressed between theelectrodes an electrical discharge of the gas will be caused and provideluminescence to display a character, such as a letter or a figure inaccordance with the selected electrodes. Only one insulating layer,which covers one of the pair of the electrodes, is needed to effectivelyoperate the display.

A wall charge having an opposite polarity to that of the electrodevoltage is provided on the insulating layer whereby a decrease of theelectrode voltage can be prevented and the memory function, capable ofturning on (to write) and off (to erase) by impressing a write pulse oran erase pulse, is formed. The single insulating layer enables adecrease of the operation voltage, a high resolution and an accuratewriting and erasing to be realized.

3 Claims, 5 Drawing Figures PATENIEU FEB] 1 I975 FIG.I

FIG.4

FIG. 5

FIG.3

1 PLASMA DISPLAY PANEL DEVICE BACKGROUND OF THE INVENTION 1. Field ofthe Invention This invention generally relates to a plasma display paneldevice, and more particularly to a plasma display panel device havingelectrodes which form a matrix or mosaic type pattern for displayingcharacters, such as letters or figures.

2. Description of the Prior Art In the past, various types of plasmadisplay devices having matrix type electrodes have been developed. Aseparate insulating plate was adhesively provided on each of two groupsof electrodes which were faced with each other.

The insulating plates provided, by electrostatic charge, a wall voltagewhich was of an opposite polarity to the applied electrode voltage,whereby the decrease of the electrode voltage would be prevented, andthe memory function, capable of writing and erasing, was formed byimpressing a write pulse or an erase pulse and thereby provided thedesired operation.

While somewhat satisfactory, since the insulating plates wererespectively provided on each group of electrodes, two sheets of theinsulating plates between the two groups of electrodes were required andaccordingly, the electric field intensity in the discharging gap wasrelatively low compared to the voltage impressed on the electrodes. As aresult thereof a relatively high operation voltage was needed.

Moreover, the concentration of the electric field distribution on theelectrodes was adversely affected by the insulating plates and broadenedthe discharge thereby preventing the attainment of a high resolution.

An additional problem with the prior art display panel device was thatsince the discharging gap was surrounded by the insulating plates, itwas hard to provide the required free electrons which were necessary forthe initiation ofa discharge, thereby causing inaccurate writings tooccur.

Still further in the past, it was also hard to locate the timing of theimpressed pulses, during the discharge, for eliminating the wall chargeat the time of turn off.

One attempt in the past to improve the above problems was to improve theelectric field condition in the discharging gap by using thinnerinsulating plates. Accordingly, insulating plates having 50 14pm ofthickness were preferably used. -A problem here was that such plateshave the disadvantage of being too brittle and were hard to make.

SUMMARY or THE INvENTIoN' It is an object of this invention to provide'anew and improved unique plasma display panel device.

It is another object of this invention to provide a new and improvedunique plasma display panel device capable of operating at a relativelylow voltage and which provides a high resolution for increasingreliability in writing and erasing.

It is still another object of this invention to provide a new andimproved unique plasma display panel which is easily prepared by fixingan insulating layer to only one group of electrodes.

yet one further object of this invention is to provide a new andimproved unique plasma display panel device wherein one group ofelectrodes are formed in a mosaic type pattern to simplify the displaydriving cir- Briefly, the foregoing and other objects are in one aspectattained in accordance with this invention by the provision of a plasmadisplay panel device having a first group of electrodes which areprovided on one surface of a first transparent insulating base plate anda second group of electrodes positioned to face the first group ofelectrodes and being provided on a surface of a second insulating baseplate. Only one insulating layer is provided between the first group ofelectrodes and the second group of electrodes. A spacer is provided andforms an airtight sealed gap between the first group of electrodes andthe second group of electrodes through the single insulating layer. Adischargeable gas is charged in the gap formed. between the first groupof electrodes and the second group of electrodes such that an electricaldischarge of the gas is caused to display a character.

DESCRIPTION OF THE DRAWINGS These and other objects and advantages ofthis invention will become more readily appreciated by reference to thefollowing detailed description, when considered in connection with theaccompanying drawings,

wherein:

FIG. 1 is a partial cross-sectional schematic view of one embodiment ofa conventional prior art plasma display panel device;

FIG. 2 is a partial cross-sectional schematic view of one preferredembodiment of a plasma display panel device using matrix type electrodesin accordance with this invention;

FIG. 3 is a partial cross-sectional schematic view of another preferredembodiment of the plasma display panel device using matrix typeelectrodes in accordance with this invention;

FIG. 4 is a front sectional view of still another pre ferred embodimentof the plasma display panel device 'using mosaic type electrodes inaccordance with this invention; and

FIG. 5 is a schematic view of a segment electrode used for theembodiment of FIG. 4 for displaying a mo saic type numeral figure.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS a thin'insulatingglass plate (2 and (2a). The glass plates (2) and (2a) are separatedd'bya spacer (l) to thereby form a discharging cell. Two transparentreinforcing glass plates (4) and (4a) are further provided and each ofthe same has a respective group of a plurality of strip type electrodes(3) and (3a) adhered on an outer surface of the insulating glass plates.A dischargeable gas, such as neon, is sealed in a discharging gap (5)which is located between the two separated sheets of the insulatingglass plates (2) and (2a). An A.C. voltage is impressed between the twogroups of the electrodes (3) and (3a) for electrically discharging thegas at the points of inter-section (6) of the electrodes (3) and (3a) tothereby sustain a luminescence, once turned on by a write pulse untilturned off by an erase pulse.

The main function of the thin insulating glass plates (2) and (20)between the groups of electrodes (3) and (3a) and the discharging gap(5) is to separately trap ions and electrodes which are generated by thedischarge and which are moved to different directions by the electrodevoltage. In accordance with the charges so formed, a wall voltage havingan opposite polarity to that of the electrode voltage is provided. Thewall voltage will increase, depending upon the discharge, to therebydecrease the electrode voltage and to finally stop the discharge, suchas to prevent any decrease or deterioration of the electrode which couldbe caused by a severe discharge.

The insulating glass plates (2) and (2a) enable the memory functionwhich is one of the most advantageous characteristics of the displaypanel to be provided. The memory function results from the fact thatportions of the applied A.C. voltage are lower than that necessary forcausing ignition of a discharge and the same are usually impressed onthe electrodes. When a lighting is required and the voltage of a narrowwidth pulse is impressed for causing a discharge, the wall voltage isformed to thereby reverse the polarity of the A.C. voltage, whereby thepolarity of the wall voltage will coincide with that of the A.C.voltage. The wall voltage is thus combined with the A.C. voltage.

Accordingly, even though the A.C. voltage is low, a voltage which ishigher than that required for ignition of a discharge will be impressedon the discharge gap so that the discharge is intermittently repeatedfor each reversing of the polarity of the applied A.C. voltage.

electrodes. This results in the requirement of a high voltage operation.The concentration of the electric field distribution on the electrodesis also adversely affected by the insulating glass plates and tends tobroaden the discharge, preventing a high resolution from being realized.Moreover, since the discharge gap is surrounded by the insulatingplates, it is hard to generate the free electrons required for theinitiation of the discharge, whereby the accuracy-of lighting isinferior.

Referring now to the present invention, it will be seen that theabove-mentioned disadvantages can be removed by providing an insulatingmaterial such as an insulating glass plate on the surface of only onegroup of electrodes. The other insulating material is eliminated.

FIG. 2 is a schematic view of one preferred embodiment of a plasmadisplay panel device .in accordance with this invention. The plasmadisplay panel device is shown as including a pair of the reinforcingglass plates (4) and (4a) which are positioned'to face with each otherand which respectively have a plurality of crossed conductive strip typeelectrodes (3) and (3a). Only one sheet of an insulative layer (2), suchas an insulating glass plate, is provided between the pair ofreinforcing glass plates (4) and (4a). A spacer (l) is provided betweenthe insulating layer (2) and one of the pair of the glass plateelectrodes (3) or (3a).

It should be understood that at least one of the reinforcing glassplates (4) and (4a) should be made transparent, so that the luminescencecaused by a gaseous discharge can be seen exterior to the device.

It should further be understood that the strip type electrodes (3) fixedto the reinforcing glass plate (4) are arranged in parallel in ahorizontal direction while the strip'type electrodes (3a) fixed to thereinforcing glass plate (4a) are arranged in parallel in a verticaldirection. The two groups of electrodes (3) and (3al thereby form matrixtype electrodes which three dimensionally cross each other.

The insulating layer, such as the sheet of the insulating glass plate(2), is directly fixed on the strip type electrodes (3a) of thereinforcing glass plate (4a) and thereby covers the electrodes (3a). Theinsulating glass plate (2) is made of a material which is capable offorming a wall charge and is preferably glass having a high content oflead and a low melting temperature point. The invention is not solimited, however, and it is possible to use a heat resistant organicmaterial, such as polyimide or polyamide, for the insulating glass plate(2). The spacer (1) is made of either an insulating or a conductivematerial and is fixed to the surface of the insulating layer (2) whichis opposite to that surface which is fixed to the electrodes (3a). Thereinforcing glass plate (4a) which has one group of the electrodesattached thereto is arranged so as to connect the spacer (I) to thereinforcing glass plate (4) which has the other group of electrodesattached thereto. A discharging gap (5) is formed between both groups ofthe electrodes (3) and (3a) for charging a dischargeable gas, such asneon, in the discharging gap. The groups of electrodes (3) and (3a) andthe insulating layer (2) forms an air-tight seal.

In operation, when an A.C. voltage impressed to cause an electricdischarge on the strip type electrodes selected from the groups of theelectrodes (3) and (3a), the electrons or ions so generated will betrapped on the insulating layer (2) in accordance with the'polarity ofthe electrode voltage and thereby form a wall voltage. It should beunderstood that the electrode voltage is cancelled by the wall voltagein order to prevent a severe discharge. When the polarity of the A.C.voltage impressed on the electrodes is reversed, then the same willcoincide with that of the wall voltage so that the A.C. voltage will beadded to the wall voltage and electrodes, shows as group (3), is exposedin the discharging gap (5), the electric field intensity in the discharging gap (5) will be relatively high compared with that of the priorart wherein two insulated layers were used. Accordingly, the operationvoltage can be decreased. Since with the present invention, theconcentration of the electric field on the electrodes is high, a panelhaving high resolution and writing and erasing is formed.

Also with the present invention because of the mobility of the ions inthe discharging gap, it should be apparent that when the polarity of theexposed group of electrodes is positive and the polarity of theinsulating group of electrodes is negative and an erase pulse isimpressed, it will be easy to eliminate the wall charge and therebyaccurately erase the luminescence.

FIG. 3 is another embodiment of the plasma display panel device of thisinvention, wherein spacers (l) and (1a) are respectively fixed to bothsurfaces of the single sheet of the insulating layer (2) and each groupof the electrodes (3) or (3a) is attached to each spacer to thereby formtwo discharging gaps (5) and (5a) on both sides of the insulating layer(2).

In this embodiment, it should be understood that the electrons and theions are trapped on the insulating layer (2) to form the wall voltage ina manner like that of the embodiment shown in FIG. 2. Accordingly, it isagain possible to avoid a severe discharge and to provide the desiredmemory function. Since in the present embodiment both groups of theelectrodes are exposed in each of the discharging gaps, it is possibleto provide the advantage of a decrease in the operation voltage toresult in a high resolution display device having high writing anderasing accuracy.

The above described embodiments use two groups of a plurality of striptype electrodes (3) and (3a) which I are arranged in a matrix form.However, the means for impressing a voltage to the matrix shapedelectrodes is complicated, when the embodiment is used for simplydisplaying numerical figures, and the like. Under such conditions themosaic shaped electrode is preferred, as hereinafter described.

FIG. 4 is a front sectional view of a display panel in accordance withthis invention for displaying characters. In FIG. 4, the referencenumeral (4a) designates a transparent glass base plate and the referencenumeral (7) designates segment electrodes which show a numericalcharacter in a mosaic form. The segment electrodes (7) are fixed on thesurface of the glass base plate (40). Each electrode has a terminal forenabling a voltage to be impressed thereon. The reference nu- 'meral (2)designates a transparent insulating layer,

such as glass, which covers the segment electrodes (7). The referencenumeral (1) designates a spacer, and the reference numeral (8)designates a position setting electrode having a plate or net shape andhaving a terminal for impressing a voltage thereon. The position settingelectrode (8) is fixed on the insulating base plate (4), such as made ofglass or ceramic. The glass base plate (4a), having the electrodes (7and the base plate (4), having the electrode (8), are faced with eachother and are air-tight sealed through the spacer (l) to preserve thegap (5), wherein neon or the like is charged to form a gas therein.

A display element (9) for displaying characters is thus formed by thecombination of the electrodes (7), the electrode (8) and the gas gap(5). It should be understood that a desirous number of such displayelements are arranged to form a numeral display panel for enabling manycharacters to be displayed.

In the embodiment shown in FIG. 4, the segment electrodes (7) arecovered by the insulating layer (2), however, it is possible to modifythe same such that the position setting electrode (8) is covered by theinsulating layer and thereby expose the segment electrodes ('7) in thegas gap (5).

It is also possible to modify the embodiment of FIG. 4 such that asingle continuous metal plate of sufficient strength can be used as theposition setting electrode (8) thereby eliminating the base plate (4),if the gap between the groups of electrodes can be air-tight sealed.

It is also possible with the embodiment of FIG. 4 to provide othermodifications such as having the base plate (4) formed into one piecewith the spacer (I). In the plasma discharge system of the presentembodiment, it is possible as is well known to provide a memory functionby impressing a write pulse having a voltage such as of 10 KH betweenthe electrodes (7) and the electrode (8) to maintain the plasmadischarge along the segment electrodes (7) and thereby to display acharacter. On the other hand, it is well known that it is possible toeliminate the display by impressing an erase pulse.

When the shape of the numerical character shown in FIG. 5 is used as amosaic type letter, it should be understood that the number of segmentelectrodes (7) is 7, while the number of position setting electrodes (8)is 1. Accordingly, it is possible to display the numeral of I (6) and adot and non-mark by selectively impressing a voltage to the eightelectrodes, whereby the display driving circuit is greatly simplified ascompared to one using matrix type electrodes.

As stated above, it should now be apparent that in accordance with thisinvention, the manufacture of a display device is simplified since onlyone insulating glass plate is used for arranging two groups ofelectrodes. Moreover, the important functions of providing a decrease inthe operation voltage, having a high resolu tion and having accuratewriting and erasing, is greatly improved compared to that of theheretofore conventional display panel devices.

Obviously, numerous modifications and variations of the presentinvention are possible in light of the above teachings. It is thereforeto be understood that within the scope of the appended claims theinvention may be practiced otherwise than as specifically describedherein.

Accordingly, what is claimed as new and desired to be secured by LettersPatent of the United States is:

1 A plasma display panel comprising: I

a first base plate having an inner surface and an outer surface,

a first electrode disposed adjacent to'the inner surface of the firstbase plate, I a second base plate having an inner surface and an outersurface, aspacer disposed between the first base plate and the secondbase plate,

a second electrode disposed adjacent to the inner surface of the secondbase'plate,

the second electrode being further disposed opposite the first electrodeand a gap formed therebetween by said spacer,

a continuous insulating layer having an inner surface and an outersurface disposed within the gap, the gap being otherwise occupied in itsentirety by a dischargeable gas,

the first electrode being disposed between the inner surface ofthe firstbase plate and the outer surface of the insulating layer,

whereby an electrical discharge of the gas in the gap occasioned byapplication of a voltage of a given polarity to the first and secondelectrodes establishes a wall voltage of opposite polarity on the innersurface of the insulating layer.

2. A plasma display panel in accordance with claim 1 wherein one of theelectrodes comprises a plurality of electrode segments.

the first electrode and a gap formed therebetween by said spacers,

a continuous insulating layer having first and second surfaces disposedwithin the gap,

the gap being otherwise occupied in its entirety by a dischargeable gas,

the insulating layer being so disposed so as to permit a first portionof the dischargeable gas to be disposed between the first electrode, thefirst spacer and the first surface of the insulating layer and' being sodisposed so as to permit a second portion of the dischargeable gas to bedisposed between the second electrode, the second spacer and the secondsurface of the insulating layer.

1. A plasma display panel comprising: a first base plate having an innersurface and an outer surface, a first electrode disposed adjacent to theinner surface of the first base plate, a second base plate having aninner surface and an outer surface, a spacer disposed between the firstbase plate and the second base plate, a second electrode disposedadjacent to the inner surface of the second base plate, the secondelectrode being further disposed opposite the first electrode and a gapformed therebetween by said spacer, a continuous insulating layer havingan inner surface and an outer surface disposed within the gap, the gapbeing otherwise occupied in its entirety by a dischargeable gas, thefirst electrode being disposed between the inner surface of the firstbase plate and the outer surface of the insulating layer, whereby anelectrical discharge of the gas in the gap occasioned by application ofa voltage of a given polarity to the first and second electrodesestablishes a wall voltage of opposite polarity on the inner surface ofthe insulating layer.
 2. A plasma display panel in accordance with claim1 wherein one of the electrodes comprises a plurality of electrodesegments.
 3. A plasma display panel comprising: a first base platehaving an inner surface and an outer surface, a first electrode disposedadjacent to the inner surface of the first base plate, a second baseplate having an inner surface and an outer surface, first and secondspacers disposed between the first base plate and the second base plate,a second electrode disposed adjacent to the inner surface of the secondbase plate, the second electrode being further disposed opposite thefirst electrode and a gap formed therebetween by said spacers, acontinuous insulating layer having first and second surfaces disposedwithin the gap, the gap being otherwise occupied in its entirety by adischargeable gas, the insulating layer being so disposed so as topermit a first portion of the dischargeable gas to be disposed betweenthe first electrode, the first spacer and the first surface of theinsulating layer and being so disposed so as to permit a second portionof the dischargeable gas to be disposed between the second electrode,the second spacer and the second surface of the insulating layer.